Castle Geyser with geyserbow, Upper Geyser Basin, Yellowstone National Park, Wyoming--photo courtesy Kenneth Barrick
Upon the announcement last week ("Government expands geothermal energy leasing") that the Interior Department plans to make available 190 million acres of federal land for geothermal energy development, it is worth visiting the research of Kenneth A. Barrick, UAF associate professor of geography. Barrick has extensively studied the extinction of geysers following energy development. Below is a brief summary of Dr. Barrick's geyser work.
Geyser basins are rare composite resources that provide an important array of recreational, scientific, cultural, national heritage, and economic benefits. For centuries, hydrothermal recreation has supported tourism—from “geyser gazing” to the “taking of the waters” in spa thermal pools. However, geysers are relatively fragile geologic features that are subject to irreversible damage and quenching from nearby human development activities. Geyser basins have been damaged or driven to extinction by geothermal well withdrawal (home heating and/or electricity production), alteration of adjacent riverbeds or river discharge relationships, filling of hydroelectric reservoirs, and exploration for precious metals. Over the past few decades, various energy development projects have permanently quenched about 260 geysers, which reduced the worldwide geyser endowment by about 23 percent (or 40 percent of all geysers located outside of national parks and reserves). About 100 geysers were quenched in New Zealand (75 percent of the local endowment), and about forty six in Iceland (75 percent of the local endowment). In the U.S., two geyser fields in Nevada were quickly driven to extinction by geothermal wells at Beowawe (all 30 geysers), and Steamboat Springs (all 26 geysers).
The world’s few remaining geyser basins are exceptionally rare. However, the increasing demand for alternatives to fossil fuel will likely increase the prospects for geothermal energy development. Therefore, the sustainability of the world’s remaining geyser basins requires that environmental managers and engineers understand the threat that geothermal wells pose when developed on the same hydrothermal field with geysers and important hot springs. Geysers almost always occur in association with other surface hydrothermal features, including hot springs, fumaroles, mud pots, and steaming ground. When geysers and associated hydrothermal features cluster around a common watershed and geothermal heat source, they constitute a composite resource—often referred to as a “geyser basin” (in New Zealand, “hydrothermal area”). Technically, a geyser is a hot spring that intermittently becomes unstable and erupts (usually upwards) a turbulent jet of water and steam.
The Earth’s natural endowment before the geyser extinctions caused by energy development projects was about 1,194 geysers. A total of about 260 geysers have permanently ceased to play as a result of nearby development activities. Today, most of the remaining geysers are found in only five major clusters, including: (1) Yellowstone National Park (about 500 geysers); (2) Dolina Geizerov, “Valley of Geysers” in Russia (about 190 geysers); (3) El Tatio in northern Chile (about eighty geysers); (4) the Taupo Volcanic Zone in New Zealand (about 30 remaining geysers); and (5) Iceland (about 16 remaining geysers, not all active).
The most serious concern for the future sustainability of the world’s remaining geyser basins is the prospect of nearby geothermal energy development. Several factors are conspiring to increase the prospects for geothermal energy. First, the search for alternative energy resources will accelerate with the increasing cost of fossil fuels. Second, technological advancements have reduced the size of geothermal power plants to 5 megawatts (MW), and lowered the cost of developing geothermal fields through staged development. The next generation of technology, called “Enhanced Geothermal Systems,” is expected to make large-scale “heat mining” possible through deep-drilling and reservoir stimulation techniques (1 to 50 MW). Enhanced geothermal systems will push development from the relatively restricted domain of high-temperature geothermal fields (in the U.S., mostly limited to the western states) to all landscapes. Third, emerging centers of expertise in geothermal engineering (like those in Iceland) are maturing into export industries.
Geothermal energy production requires wells that extract large amounts of hot water, steam and/or heat from the hydrothermal reservoir. Geothermal well withdrawal is capable of quenching natural overflow features like geysers. When geothermal wells lower reservoir pressure, the discharge can be reduced to the point where geysers cease to play. The often fatal resource competition is best understood as the “geyser paradox.” The thermal energy required to trigger the eruption of a geyser (150ºC or higher) indicates a shallow magmatic heat source, which is a reliable indicator of a potential geothermal energy resource. Moreover, geysers are nonrenewable resources—they almost never recover when quenched by geothermal well withdrawal. It is suspected that underground cooling clogs the geyser’s plumbing with mineral precipitates. The scarcity of the world’s remaining geysers has greatly increased their preservation value. The sustainability of the remaining geyser basins will require an integrated environmental management approach based on a comprehensive knowledge of the values and benefits that society derives from them; a sober accounting of the known risks of competition for heat and/or water from the hydrothermal reservoir that supplies them, and effective protection legislation.
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